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    <title>fgrayplot</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : 08/12/2006</div>
    <p>
      <b>fgrayplot</b> -  2D plot of a surface defined by a function using colors</p>
    <h3>
      <font color="blue">Calling Sequence</font>
    </h3>
    <dl>
      <dd>
        <tt>fgrayplot(x,y,f,[strf,rect,nax])  </tt>
      </dd>
      <dd>
        <tt>fgrayplot(x,y,f,&lt;opt_args&gt;)  </tt>
      </dd>
    </dl>
    <h3>
      <font color="blue">Parameters</font>
    </h3>
    <ul>
      <li>
        <tt>
          <b>x,y</b>
        </tt>: real row vectors.</li>
      <li>
        <tt>
          <b>f</b>
        </tt>: external of type <tt>
          <b>y=f(x,y)</b>
        </tt>.</li>
      <li>
        <tt>
          <b>&lt;opt_args&gt;  </b>
        </tt>: This represents a sequence of statements <tt>
          <b>key1=value1, key2=value2</b>
        </tt>,... where <tt>
          <b>key1</b>
        </tt>, <tt>
          <b>key2,...</b>
        </tt> can be one of the following: rect, nax, strf or axesflag and frameflag (see <tt>
          <b>plot2d</b>
        </tt>).</li>
      <li>
        <tt>
          <b>strf,rect,nax</b>
        </tt>: see <tt>
          <b>plot2d</b>
        </tt>.</li>
    </ul>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
      <tt>
        <b>fgrayplot</b>
      </tt> makes a 2D plot of the surface given by <tt>
        <b>z=f(x,y)</b>
      </tt> on a 
    grid defined by <tt>
        <b>x</b>
      </tt> and <tt>
        <b>y</b>
      </tt>.
    Each rectangle on the grid is filled with a gray or color level depending 
    on the average value of <tt>
        <b>z</b>
      </tt> on the corners of the rectangle.</p>
    <p>
    Enter the command <tt>
        <b>fgrayplot()</b>
      </tt> to see a demo.</p>
    <h3>
      <font color="blue">Examples</font>
    </h3>
    <pre>

t=-1:0.1:1;
deff("[z]=my_surface(x,y)","z=x**2+y**2")
fgrayplot(t,t,my_surface,rect=[-2,-2,2,2])
 
  </pre>
    <h3>
      <font color="blue">See Also</font>
    </h3>
    <p>
      <a href="grayplot.htm">
        <tt>
          <b>grayplot</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="plot2d.htm">
        <tt>
          <b>plot2d</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="Sgrayplot.htm">
        <tt>
          <b>Sgrayplot</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="Sfgrayplot.htm">
        <tt>
          <b>Sfgrayplot</b>
        </tt>
      </a>,&nbsp;&nbsp;</p>
    <h3>
      <font color="blue">Author</font>
    </h3>
    <p>J.Ph.C.</p>
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